Reinforced tray for delicate devices

ABSTRACT

A tray for storing and handling delicate components is strengthened with a reinforcement bar. Reinforcement bars are arranged in parallel to enhance resistance against cracking and warpage of the tray. Each reinforcement bar may include a support structure. A radius on all or a portion of tray members having a sharp edge may serve to strengthen the tray further. Tray members including ribs, openings, indentations, and pockets can have all or part of their sharp edges covered with a radius.

BACKGROUND OF THE INVENTION

The invention pertains to the storage and handling of delicate components, such as semiconductors, and to the transport of such components in a tray assembly. More specifically, the invention pertains to trays reinforced to enhance their resistance against warpage, cracking, and other types of distortion.

DESCRIPTION OF THE PRIOR ART

FIG. 1 is a plan view of prior art tray 100. Tray 100 is shown as having an array of pockets. Adjacent to at least some of the pockets are ribs for strengthening the tray against cracking.

During manufacturing and subsequent use and handling, stresses can cause trays to crack, warp or otherwise become unsuitable for storing delicate components. Up to now, trays have been known to be provided with ribs adjacent to each pocket to enhance the tray's resistance to cracking.

In addition binding a multiplicity of trays with a strap can also induce warpage and cracking in a stack. Consequently a need exists for a tray that is better reinforced against cracking and warpage.

SUMMARY OF THE INVENTION

The invention pertains to a tray that has been reinforced with a reinforcement bar and a support structure near the edge of the tray. The tray is also provided with an indentation that facilitates stacking and strapping of a stack of trays.

Another embodiment of the present invention is a tray assembly for storing components in a stack, where each tray in the tray assembly is reinforced with a ridge on one side of the tray. The ridge extends along a substantial part of the tray and extends inward relative to the pockets to form a reinforcement bar that imparts enhanced resistance to warpage. A support structure occupying a space between the reinforcement bar and the edge of the tray may also be present. Such a support structure may comprise one or more protrusions. Each protrusion may have a primary axis in a direction generally orthogonal to the tray edge.

Yet another embodiment concerns providing a rounded portion (or radius) on corner regions of a reinforcement bar. The invention has been found to result in greater structural integrity by enhancing resistance to cracking and warpage in plastic trays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a prior art tray.

FIG. 2 is a perspective view of a tray assembly of the present invention.

FIG. 3 is a magnified top view of the reinforced section of a tray of the present invention.

FIG. 4A is a magnified perspective view of the reinforced section of a tray of the present invention.

FIG. 4B is a magnified perspective view of the underside of the tray of FIG. 4A.

FIG. 5 is a cross-sectional view taken along V-V in FIG. 4A.

FIG. 6A is a perspective view of a support structure of the present invention.

FIG. 6B is a perspective view of a support structure of the present invention.

FIG. 6C is a perspective view of a support structure of the present invention.

FIG. 7A is a partial view of an upper side of a tray that includes radii.

FIG. 7B is an exploded view of the tray of FIG. 7A.

FIG. 8A is a cross-sectional view taken along I-I of FIG. 7.

FIG. 8B is a top view of Region II of FIG. 7.

FIG. 9 is a cross-sectional view taken along IX-IX of FIG. 7.

FIG. 10 is a partial view of the underside of the tray of FIG. 7.

DETAILED BRIEF DESCRIPTION OF THE INVENTION

The present invention discloses a tray for protecting delicate components from damage during transport or “drop testing”. If the trays are bend or twisted, tensile stress on the top surface will build up and may cause a crack to propagate. As a result, the tray will become distorted and its contents vulnerable to damage. The present invention mitigates the tensile stress by including various design features that maintain the structural integrity of the tray. The trays of the present invention are suitable for storing components such as semiconductors, electronic devices, work pieces, and medical instruments.

FIG. 2 illustrates how a stack of trays can be bound together in accordance with the present invention. The trays of this invention preferably have a length ranging from 310 mm-320 mm; a width of 130 mm to 141 mm; and a height ranging from 5.00 mm to 7.0 mm. In addition, each tray has a plurality of indentations 25 on the underside for receiving a strap 28. Strap 28 is used to bind the stack of trays together. Indentation 25 preferably has a width “X” between 25 and 26 mm, and a height “Y” of between 2.0 and 3.0 mm. In a more preferred embodiment, the width of the indentation is between 25.30 mm and 25.75 mm, while the height is between 2.40 mm and 2.70 mm. An edge 20 surrounds tray 200 to form a generally rectangular plane having sides 20A, 20B, 20C, and 20D. Within this plane is a ridge 32 near the periphery of the first, upper side of the tray. FIG. 3 illustrates how a portion of ridge 32 extends inward in the vicinity of indentation 25 relative to the pockets to form a reinforcement bar 35 for enhancing resistance to warpage.

Tray 200 has a plurality of pockets 30 in an array as shown in FIG. 3. A plurality of ribs 39 are located adjacent at least some of the pockets 30. Ribs 39 serve to strengthen a tray's resistance against cracking, but such ribs have been found to be inadequate when used alone. However, such ribs are not essential in all embodiments of this invention. Therefore, in the present invention, one or more reinforcement bars 35 are present along the periphery of tray 200. On the top side of each tray is a reinforcement bar 35 that is more clearly shown in FIG. 3. In a preferred embodiment, where there is a first reinforcement bar on one, upper side of the tray, a second reinforcement bar is located parallel to the first on the same, upper side as the first reinforcement bar but along another edge. So, for example, a reinforcement bar may be located parallel to sides 20B and 20D near indentations 25 at each of those sides.

FIG. 4A illustrates a magnified view of the reinforcement bar 35. Reinforcement bar 35 has a width H1 of between 2.5 and 5.5 mm, more preferably the width ranges from 3.0 to 4.5 mm. The distance from the edge 20 to reinforcement bar or H2 is between 4.0 and 7.0 mm (±1.0) More preferably, the distance H2 ranges from 4.5 to 6.5 mm (±1.0). In one embodiment, Reinforcement Bar 35 may be supported by a support structure 37. As shown in FIG. 4A, support structure 37 preferably comprises three segments 37A, 37B, and 37C. Each such segment is preferably orthogonal to edge 20D, and also to reinforcement bar 35.

In a preferred embodiment, support structure 37 contacts reinforcement bar 35. However, it is not essential for the invention that support structure 37 be present or that support structure 37 extend into reinforcement bar 35. The support structure 37 may simply occupy some portion of the space 40 between reinforcement bar 35 and edge 20 and still adequately enhance the tray's resistance to warpage.

By providing trays with the reinforcement bar 35 and support structure 37, warpage of no more than 390 mils results during testing. More specifically, it was found that strapping the tray assembly of FIG. 2 at 20 kg force over a temperature range of 125° C.-175° C. for a period of 24 hours resulted in a warpage of no more than 30 mils. An indentation 25 is located adjacent to the support structure 37 as shown in FIGS. 4A. FIG. 4B is the bottom side of tray 200. The invention of FIG. 4B could be used in conjunction with a rib 45 that functions to further strengthen the tray

A cross-section of reinforcement bar 35 and one of the protrusions of support structure 37 is shown in FIG. 5. Section 37C corresponds to an element of the support structure and has a thickness ranging from 1.0 mm-2.0 mm with a tolerance for each dimension of ±0.50 mm. The height of the reinforcement bar measured from an upper surface of the tray to the top surface of reinforcement bar 37 (designated as K) is 1.60 mm to 3.25 mm (±1.0 mm). The thickness of the tray (T1) is between 1.0 mm-2.0 mm (±0.75 mm). Of course, the dimension for each element in FIG. 5A can be varied in accordance with the overall dimensions of the tray and the desired tray characteristics.

In addition, it is not essential to the invention that 37A-37C of the support structure have a rectilinear shape. For example, one or more segments of the support structure may instead have a rod-like shape (FIG. 6A), triangular (FIG. 6B), or trapezoidal shape (FIG. 6C). Furthermore, the support structure 37 may have fewer or more than the three illustrated segments 37A-37C. Such segments need not be at a right angle to the edge of side 20A.

FIG. 7A illustrates a tray 300 that is a more preferred embodiment of the invention. Tray 300 has pockets formed by wall members 65A-65D, and a floor 50. Floor 50 has a series of openings 73 that results in a substantially lightweight tray. To compensate for the vulnerability toward distortion that tray 300 is faced with, a rounded portion or radius is provided on openings 73 and on top surface 38 of Reinforcement Bar 35 as shown in FIG. 7A. Radii 35A, 35B are also present on the exterior and interior of corner regions III which is shown in FIG. 7A. Although not illustrated in FIG. 7A, corner region II may be symmetrical with region III. Specifically, it is also desirable for a radius (rounded portion) to be present on the exterior and interior of corner region II, as in corner region III.

FIG. 7B is an exploded view of tray 300 to more clearly illustrate the reinforcement bar 35. Tray 300 may be further strengthened by providing radii on the side. When the perimeter of space 42 has a radius on each side, it is not necessary to include support structure 48 to enhance the tray's resistance to cracking and warpage.

FIG. 8A illustrates a cross-sectional view of the Reinforcement Bar 35 taken along I-I perimeter of 42, which is located at the base of reinforcement bar 35. Specifically, rectangular space 42 has a perimeter bounded on 3 sides by a lower surface of the reinforcement bar 35 and on the fourth side by an inner wall 77. Inner wall 77 is parallel to wall 87 (shown in FIG. 7A). Preferably the perimeter of 42 will have a radius on each in FIG. 7A. Preferably, the top of reinforcement bar will have radii located at 82A and 82B. To form a more robust tray, radii can also be placed at locations 84A and 84B. A top view of corner region III is shown in FIG. 8B. As shown in FIG. 8B, both the interior 88A and exterior upper surfaces 88B of corner region III are provided with a radius. By including radii in corner regions II and III, tray 200 maintains its structural integrity when stressed during storage, transport or handling.

FIG. 9 illustrates more clearly the radii present in openings 73, through a cross-sectional view taken along IX-IX of FIG. 7. The radius of curvature for openings 73 ranges from 0.20-0.25 mm. Radii 94A and 94B correspond to surfaces of opening 73A. Radii 94C and 94D correspond to surfaces of opening 73B. Preferably all of the openings 73 of floor 50 are provided with a radius. In this manner the stress on the sharp edges is relieved and the tray is more resistant to crack propagation.

Tray 300 has an upper side 320 shown in FIG. 7A and 7B, and a lower side 340, shown in FIG. 10. FIG. 10 illustrates several openings 73, each of which preferably have a radius 75. Each side of tray 300 has an outer edge. Specifically, outer edge 70 of upper side 320 and outer edge 72 of lower side 340 are shown in FIGS. 7A and 10 respectively. Optionally the invention may include a radius along the perimeter 70, 72 of both sides of the tray. On side 320, a first radius may be present where edge 70 intersects with top surface 34. FIG. 10 illustrates a second radius where edge 72 intersects with surface 34. The radii shown on edges 70 and 72 preferably have a radius of curvature greater than the radii present on openings 73.

The maximum radius for any sharp edge of a tray of the present invention preferably does not exceed one half of the thickness of the member having the radius. In addition, the minimum radius of any member preferably does not go below 0.20 mm. The preferred radii for any sharp edge of the tray will fall within the range of 0.25 to 1.5 mm. The above radius ranges are merely preferred and the skilled artisan would recognize that other ranges could be suitable as well depending on the circumstances.

FIG. 10 shows the exterior edge 25A of indentation 25 also provided with a radius. In general it is preferred that all the sharp edges on tray 300 are replaced with rounded contour, or radii. However, it is not essential for edges 70 and 72 of tray 300 to have a radius in order to maintain the structural integrity of tray 300.

Preferably, the trays of the present invention have a unitary structure wherein the entire structure is formed simultaneously in a single mold. Although several embodiments have been described as having radii, it is understood that the radius on any portion of the tray may be ellipsoidal or have a shape other than a segment of a circle. In addition, a chamfer may be used instead of a radius on the openings, reinforcement bar and perimeter of tray 300.

The present invention is fabricated from traditional methods of injection molding. Suitable manufacturing materials for the present invention include conductive, thermoplastic, non-conductive, and insulated plastic. In addition, the trays of this invention can be fabricated from material that has electrostatic dissipating properties.

The specific examples provided above are intended to be illustrative of the invention only. It should be apparent to those skilled in the art that various features of the invention may be modified without departing from the spirit and scope of the invention. All ranges set forth herein are intended to be exemplary and not limiting in scope. As those of ordinary skill in the art can appreciate that such parameters as the tray dimension, radii ranges, and the dimensions of various tray members can be optimized to encompass other ranges than those that are set forth herein. It is therefore the intent that the scope of the invention is to be defined by the appended claims. 

1. A tray assembly for storing components in a stack, each tray in the tray assembly having a first side and a second side, said tray assembly comprising: a) an array of pockets on said first side; b) a ridge on the periphery of said first side, wherein a portion of the ridge extends inward relative to the pockets to form a reinforcement bar having a first and a second corner region; c) an edge surrounding each of said sides; and d) a radius on at least one of the corner regions of the reinforcement bar.
 2. The tray assembly of claim 1, wherein each tray further includes a radius at an area adjacent to the first side of the tray.
 3. The tray assembly of claim 1, wherein each tray further includes a support structure occupying a space between the reinforcement bar and the edge, wherein said support structure protrudes from one of said sides.
 4. The tray assembly of claim 1, further comprising at least one indentation on the edge of the tray, said indentation for receiving a strap.
 5. The tray assembly of claim 3, wherein the stack is secured by aligning at least one strap over the indentation of each tray, and adhering the ends of the strap together.
 6. The tray assembly of claim 1, wherein a warpage of no more than 30 mils results from strapping the tray assembly at 20 kg force over a temperature range of 125° C.-175° C. for a period of 24 hours.
 7. A tray assembly for storing components in a stack, each tray in the tray assembly having a first side and a second side, said tray assembly comprising: c) an array of pockets on at least one of said sides; d) a ridge on the periphery of said first side, wherein a portion of the ridge extends inward relative to the pockets to form a reinforcement bar; c) an edge surrounding each of said sides; and d) a support structure occupying a space between the reinforcement bar and the edge, wherein said support structure protrudes from one of said sides.
 8. The tray assembly of claim 7, further comprising at least one indentation on the edge of the tray, said indentation for receiving a strap.
 9. The tray assembly of claim 8, wherein the stack is secured by aligning at least one strap over the indentation of each tray, and adhering the ends of the strap together.
 10. The tray assembly of claim 7, wherein a warpage of no more than 30 mils results from strapping the tray assembly at 20 kg force over a temperature range of 125° C.-175° C. for a period of 24 hours.
 11. The tray assembly of claim 7, wherein each tray is a unitary structure. 